WORST_CASE(?,O(n^3))

Solution:
---------

  append :: [b(1, 0, 0) x b(0, 0, 0)] -(2)-> b(0, 0, 0)
  attach :: [a(0, 0, 0) x b(5, 0, 0)] -(5)-> b(0, 0, 0)
  cons :: [a(0, 0, 0) x b(1, 0, 0)] -(1)-> b(1, 0, 0)
  cons :: [a(0, 0, 0) x b(5, 0, 0)] -(5)-> b(5, 0, 0)
  cons :: [a(0, 0, 0) x b(8, 12, 4)] -(8)-> b(0, 8, 4)
  cons :: [a(0, 0, 0) x b(0, 0, 0)] -(0)-> b(0, 0, 0)
  nil :: [] -(0)-> b(1, 0, 0)
  nil :: [] -(0)-> b(5, 0, 0)
  nil :: [] -(0)-> b(0, 8, 4)
  nil :: [] -(0)-> b(1, 1, 6)
  pair :: [a(0, 0, 0) x a(0, 0, 0)] -(1)-> a(12, 1, 0)
  pairsp :: [b(0, 8, 4)] -(4)-> b(0, 0, 0)


Cost Free Signatures:
---------------------

  append :: [b_cf(0, 0, 0) x b_cf(0, 0, 0)] -(0)-> b_cf(0, 0, 0)
  append :: [b_cf(1, 0, 0) x b_cf(1, 0, 0)] -(0)-> b_cf(1, 0, 0)
  attach :: [a_cf(0, 0, 0) x b_cf(0, 0, 0)] -(1)-> b_cf(0, 0, 0)
  attach :: [a_cf(0, 0, 0) x b_cf(4, 0, 0)] -(2)-> b_cf(1, 0, 0)
  cons :: [a_cf(0, 0, 0) x b_cf(0, 0, 0)] -(0)-> b_cf(0, 0, 0)
  cons :: [a_cf(0, 0, 0) x b_cf(4, 4, 0)] -(4)-> b_cf(0, 4, 0)
  cons :: [a_cf(0, 0, 0) x b_cf(1, 0, 0)] -(1)-> b_cf(1, 0, 0)
  cons :: [a_cf(0, 0, 0) x b_cf(4, 0, 0)] -(4)-> b_cf(4, 0, 0)
  nil :: [] -(0)-> b_cf(0, 0, 0)
  nil :: [] -(0)-> b_cf(0, 1, 2)
  nil :: [] -(0)-> b_cf(0, 4, 0)
  nil :: [] -(0)-> b_cf(15, 11, 2)
  nil :: [] -(0)-> b_cf(1, 0, 0)
  nil :: [] -(0)-> b_cf(4, 0, 0)
  nil :: [] -(0)-> b_cf(15, 14, 2)
  pair :: [a_cf(0, 0, 0) x a_cf(0, 0, 0)] -(0)-> a_cf(0, 0, 0)
  pair :: [a_cf(0, 0, 0) x a_cf(0, 0, 0)] -(0)-> a_cf(7, 0, 15)
  pairsp :: [b_cf(0, 4, 0)] -(0)-> b_cf(1, 0, 0)


Base Constructors:
------------------
  cons_b :: [a(0, 0, 0) x b(1, 0, 0)] -(1)-> b(1, 0, 0)
  cons_b :: [a(0, 0, 0) x b(1, 1, 0)] -(1)-> b(0, 1, 0)
  cons_b :: [a(0, 0, 0) x b(0, 1, 1)] -(0)-> b(0, 0, 1)
  nil_b :: [] -(0)-> b(1, 0, 0)
  nil_b :: [] -(0)-> b(0, 1, 0)
  nil_b :: [] -(0)-> b(0, 0, 1)
  pair_a :: [a(0, 0, 0) x a(0, 0, 0)] -(0)-> a(1, 0, 0)
  pair_a :: [a(0, 0, 0) x a(0, 0, 0)] -(1)-> a(0, 1, 0)
  pair_a :: [a(0, 0, 0) x a(0, 0, 0)] -(0)-> a(0, 0, 1)